Please explain.
Texas v. White goes on at length and repeatedly about “indissoluble” and “perpetual” union.
Certainly a constitutional amendment could permit, or force any state out of the union.
That would have to be by widespread, nearly unanamious consent (3/4s of states plus House and Senate).
That level of political agreement would resolve the controvery between a state and the federal government that secession would normally bring to the supreme court.